$ git clone -n https://src.fedoraproject.org/rpms/backintime.git /var/lib/mock/f39-build-1468927-33814/root/chroot_tmpdir/scmroot/backintime
Cloning into '/var/lib/mock/f39-build-1468927-33814/root/chroot_tmpdir/scmroot/backintime'...
$ git fetch origin 41790c2ff63b8708c24b6d7f747a3e9a15c51cb8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/backintime
 * [new ref]         41790c2ff63b8708c24b6d7f747a3e9a15c51cb8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 41790c2 Update to 1.4.1